Charged particle beam device and inspection order calculation method for same

Abstract

A charged particle beam device 100 irradiates a sample with a charged particle beam, generates an image on the basis of secondary charged particles generated by the charged particle beam EB with which the sample is irradiated, and observes the sample. The charged particle beam device 100 comprises: a charged particle beam irradiation optical system 200; and a computer system 212 that controls the charged particle beam irradiation optical system 200. The computer system 212 calculates an inspection order in which inspection sites are irradiated with the charged particle beam so that the charged particle beam with which an arbitrary inspection site among a plurality of inspection sites is irradiated does not electrically affect an inspection site to be inspected next, and sequentially irradiates the plurality of inspection sites with the charged particle beam in the calculated inspection order.

Description

Charged Particle Beam Device and Inspection Order Calculation Method Thereof

[0001] The present disclosure relates to a technique for calculating the order of inspection sites within a field of view in a charged particle beam device, etc.

[0002] As a prior art example, a technique for determining the imaging order of defects and the stage movement speed based on the positional relationship of a plurality of observation sites on a wafer is known (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2002-310962

[0004] Observation of a sample such as a wafer may be performed by sequentially irradiating a plurality of inspection sites within an observation site with charged particles and detecting secondary charged particles generated from the inspection site for each irradiation of the charged particles. In the above technique, the influence on other inspection sites due to the charging of the inspection site by the irradiation of the charged particles is not considered.

[0005] An object of the present disclosure is to provide a technique capable of avoiding the influence on other inspection sites due to the charging of the inspection site in a charged particle beam device.

[0006] Typical embodiments of the present disclosure have the following configurations. A charged particle beam device according to an embodiment irradiates a sample disposed on a stage with an electron beam, generates an image based on secondary charged particles generated by the irradiated electron beam, and observes the sample. The charged particle beam device includes an electron beam irradiation optical system that irradiates the sample with the electron beam, and a computer system that controls the beam irradiation optical system. The electron beam irradiation optical system can irradiate the sample with the electron beam for each of a plurality of inspection sites within a field of view by deflecting the orbit of the electron beam. The computer system calculates an inspection order for irradiating the inspection sites with the electron beam so as not to give an electrical influence of the electron beam irradiated to an arbitrary inspection site among the plurality of inspection sites to the next inspection site to be inspected, and irradiates the plurality of inspection sites with the electron beam in the calculated inspection order.

[0007] A method for calculating the inspection sequence of an electron beam apparatus according to one embodiment involves irradiating a sample placed on a stage with an electron beam, generating an image based on the secondary charged particles generated by the irradiated electron beam, and observing the sample. The charged particle beam apparatus comprises an electron beam irradiation optical system for irradiating the sample with the electron beam, and a computer system for controlling the beam irradiation optical system. The electron beam irradiation optical system can irradiate the sample with the electron beam at each of a plurality of inspection sites within a field of view by deflecting the trajectory of the electron beam. The inspection sequence calculation method includes the steps of: calculating an inspection sequence in which the electron beam is irradiated to the inspection sites so as not to affect the electrical effects of the electron beam irradiated to any of the plurality of inspection sites with respect to the inspection site to be inspected next; and sequentially irradiating the plurality of inspection sites with the electron beam according to the calculated inspection sequence.

[0008] According to a representative embodiment of this disclosure, a technology for calculating the inspection order of inspection sites within the field of view can be provided. Other issues, configurations, and effects will be shown in the embodiments for carrying out the invention.

[0009] This is a schematic diagram showing an example of the configuration of the main part of the charged particle beam apparatus of the embodiment. This is a schematic diagram showing an example of waveform data obtained by the charged particle beam apparatus of the embodiment. This is a schematic diagram showing an example of the situation when the electron beam is irradiated to the nearest adjacent inspection site by the charged particle beam apparatus of the embodiment. This is a diagram showing an example of the input / output processing of the computer system of the embodiment. This is a diagram showing an example of the output result of the parameter output of the embodiment. This is a flowchart showing an example of the process for determining the first inspection order of the embodiment. This is a flowchart showing an example of the process for determining the second inspection order of the embodiment. This is a diagram showing an example of the coordinate registration GUI displayed on the display device of the embodiment. This is a diagram showing an example of the display of the field of view display area of ​​the embodiment. This is a diagram showing an example of the distance between inspection sites of the embodiment. This is a diagram showing an example of the display of the field of view display area of ​​the embodiment. This is a diagram showing an example of the log of the embodiment.

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same parts are generally denoted by the same reference numerals, and repeated descriptions are omitted. In the drawings, the representation of components may not show their actual location, size, shape, extent, etc., in order to facilitate understanding of the invention.

[0011] In explanations, when describing program-based processing, the focus may be on the program, functions, or processing units. However, the main hardware component is the processor, or a controller, device, computer system, or other system composed of such a processor. A computer system, using resources such as memory and communication interfaces as appropriate, executes processing according to the program read into memory. This realizes the specified functions and processing units. A processor is composed of semiconductor devices such as a CPU / MPU or GPU. Processing is not limited to software program processing; it can also be implemented using dedicated circuits. Applicable dedicated circuits include FPGAs, ASICs, CPLDs, etc.

[0012] The program may be pre-installed as data on the target computer system, or it may be distributed as data from the program source to the target computer system. The program source may be a program distribution server on a communication network, or a non-transient computer-readable storage medium, such as a memory card or disk. The program may consist of multiple modules. The computer system may consist of multiple devices. The computer system may consist of a client-server system, a cloud computing system, an IoT system, etc. Various types of data may be composed of structures such as tables and lists, but are not limited to these. Representations such as identification data, identifiers, IDs, names, and numbers are interchangeable.

[0013] <Charged Particle Beam Apparatus of This Disclosure> This disclosure relates to a charged particle beam apparatus that uses waveform data obtained by irradiation with a pulsed charged particle beam to inspect for electrical defects or estimate the electrical characteristics of an object under observation. The charged particle beam apparatus of this disclosure optimizes the inspection sequence of multiple inspection sites by considering the electrostatic influence of the inspection sites present within the area under observation. This will be explained in more detail below.

[0014] Charged particle beam devices, such as electron microscopes, are widely used for observing the fine structures of samples such as semiconductors and biomolecules. For example, scanning electron microscopes, a type of charged particle beam device, are used to measure the dimensions of patterns formed on semiconductor wafers and to inspect defects, for the purpose of managing process yield in semiconductor device manufacturing.

[0015] One analytical method using an electron microscope involves evaluating the electrical properties of elements formed on the surface of a sample by using the measured waveform of the time evolution of secondary charged particles (secondary electrons, backscattered electrons, etc.). Here, the electron microscope can obtain the time evolution of secondary charged particles by sequentially irradiating multiple inspection sites within the field of view of the sample with a pulsed charged particle beam.

[0016] When there are multiple inspection sites within the field of view, and a pulsed charged particle beam is irradiated onto any inspection site, the secondary charged particles cause the nearest adjacent inspection site to charge. As a result, the adjacent inspection site becomes charged. When an inspection site is performed in this charged state, the brightness value of the observed image changes. Therefore, in a charged particle beam device, this can lead to misjudgments regarding the presence or absence of defects within the field of view, or a decrease in the accuracy of measuring electrical characteristics.

[0017] Therefore, the charged particle beam apparatus of this disclosure selectively selects only distant inspection sites as the next inspection site, such that the charge of the inspection site does not affect the inspection site in the next inspection sequence. For example, the charged particle beam apparatus selects an inspection site as the next inspection site that does not have a brightness effect from secondary charged particles (secondary electrons, backscattered electrons, etc.) on adjacent inspection sites. This allows the charged particle beam apparatus to improve the accuracy of measurement and inspection.

[0018] For any given inspection site among multiple inspection sites within the field of view, the next inspection site should be located at a distance greater than the minimum distance in a predetermined inspection sequence. This distance is determined from the diffusion region of secondary charged particles, the spread of secondary charged particles, and the deterrent's settling time for accurately determining the irradiation position of the charged particle beam, using optical conditions, pulsed electron irradiation parameters, structural data, material data, laser irradiation condition data, inspection area data, and design data as inputs. The target shape includes not only plugs but also wiring patterns, and the distance is calculated by referring to the design data. The coordinates of the next inspection site can be optimized by comparing the deterrent's settling time with the decharging time or the decharge completion time. Furthermore, if the decharging time or decharge completion time is shorter than the decharrent's settling time, the coordinates of the next inspection site may be registered as the next inspection site in a predetermined inspection sequence.

[0019] <Embodiment> A charged particle beam apparatus in an embodiment of the present disclosure will be described with reference to Figures 1 to 12.

[0020] <Configuration of the charged particle beam apparatus> Figure 1 is a schematic diagram showing an example of the configuration of the main parts of the charged particle beam apparatus 100.

[0021] The charged particle beam apparatus 100 comprises a main body 200 and a controller 210 connected to the main body 200. The main body 200 further consists of an electron-optical column (hereinafter referred to as "column") and a sample chamber provided at the bottom of the column. The controller 210 is a system that controls imaging and other operations performed by the main body 200. A display device 211a, an input device 211b, and a computer system 212 are connected to the controller 210. The controller 210 and the computer system 212 may be configured as an integrated unit.

[0022] The column of the main unit 200 is a charged particle beam irradiation optical system that irradiates the sample 207 with a charged particle beam. The column of the main unit 200 comprises a charged particle gun 201, a condenser lens 202, a pulse modulator 203, an aperture 204, a deflector 205, and an objective lens 206 as its components. The electron beam EB, which is a charged particle beam emitted from the charged particle gun 201, is adjusted to a predetermined state by the condenser lens 202 and modulated into a pulsed beam by the pulse modulator 203. The electron beam EB that exits the aperture 204 has its trajectory deflected by the deflector 205 and is focused onto the sample 207 by the objective lens 206. The controller 210 controls the irradiation position of the electron beam EB on the sample 207 with high precision by controlling the components of the column: the charged particle gun 201, the condenser lens 202, the pulse modulator 203, the aperture 204, the deflector 205, and the objective lens 206.

[0023] The sample chamber is a room where samples such as wafers and coupons (broken wafer fragments) are stored. The sample chamber comprises a stage 208 and a detector 209. A sample 207 is placed on the stage 208.

[0024] Stage 208 is a sample stage on which the target sample 207, for example, a semiconductor device, is placed. Stage 208 includes a stage movement mechanism. The stage movement mechanism moves Stage 208. Stage 208 moves not only in the X and Y directions but also in the Z direction, and rotates around the XY, YX, or Z axis. Therefore, Stage 208 can move the captured field of view in the horizontal and vertical directions relative to the frontal image, or in the rotational direction within the field of view. This allows the imaging field of view to be set.

[0025] The detector 209 detects secondary charged particles (secondary electrons, backscattered electrons, etc.) generated from the sample 207 irradiated with the electron beam EB as electrical signals. The detector 209 outputs the detection signal, which is an electrical signal, to the controller 210.

[0026] The controller 210 controls the operation of the main unit 200. The controller 210 can irradiate the sample 207 with the electron beam EB for each of multiple inspection areas within the field of view by deflecting the trajectory of the electron beam EB, for example by controlling the deflector 205. More specifically, the controller 210 gives instructions such as drive control to each part. For example, the controller 210 operates the stage 208 so that the area of ​​the sample 207 to be photographed as part of the field of view is located within the field of view. Subsequently, the controller 210 changes the irradiation position of the electron beam EB within the field of view in a predetermined pattern (inspection sequence) and performs inspection of each inspection area within the field of view (FOV).

[0027] The controller 210 can be implemented, for example, by a computer or a dedicated circuit. The controller 210 includes a storage unit (not shown). The controller 210 generates an image signal based on the detection signal received from the detector 209 and stores it in the storage unit as data such as an image.

[0028] The controller 210 outputs data such as images and captured data stored in a storage unit (not shown) to the display device 211a, for example, in response to a request from the input device 211b. The controller 210 can also output data input from the input device 211b to the computer system 212 and receive data from the computer system 212.

[0029] Furthermore, the charged particle beam apparatus 100 includes a laser light irradiation device 217. The laser light irradiation device 217 removes the charge accumulated on the inspection area of ​​the sample 207. The laser light irradiation device 217 includes a laser light source 214 that generates laser light to remove the charge formed when the electron beam EB is irradiated onto the sample 207, a circuit breaker 215 that controls the irradiation time of the laser light, and a laser light path adjustment device 216 that irradiates the laser light at the same position on the sample 207 as the pulsed electron beam EB irradiates. The operation of the laser light source 214, the circuit breaker 215, and the laser light path adjustment device 216 is controlled by a controller 210.

[0030] The computer system 212 controls the stage movement mechanism that moves the stage 208, as well as the charged particle beam irradiation optical system. In this embodiment, the computer system 212 controls the optical system (column of the main body 200) that irradiates the electron beam EB by controlling the controller 210.

[0031] The computer system 212 includes a database 212a and a calculator 304. The calculator 304 stores the results of its calculations in the database 212a. The calculator 304 also executes a program stored in a memory unit (not shown) to calculate the inspection order in which the electron beam EB is irradiated onto inspection sites so that the electrical effects of the electron beam EB irradiated onto any of the inspection sites do not affect the next inspection site, and then implements the process of sequentially irradiating the multiple inspection sites with the electron beam EB in the calculated inspection order. For example, the calculator 304 determines whether the electrical effects will affect the next inspection site based on the distance between the arbitrary inspection site and the next inspection site, the time required to deflect the trajectory of the electron beam EB after irradiating the arbitrary inspection site in order to irradiate the next inspection site (i.e., the settling time of the deflector 205), and the time required for the inspection site to naturally discharge after being irradiated with the electron beam EB, and uses this determination result to calculate the inspection order. A more detailed explanation of the method for calculating the inspection sequence will be given with reference to Figures 6 and 7. Secondary charged particles obtained by irradiation with each electron beam EB are detected by the detector 209, and the sample 207 is observed within its field of view.

[0032] Furthermore, the arithmetic unit 304 takes structural data, material data, and design data of the sample 207, as well as the acceleration voltage and probe current of the electron beam EB, the area of ​​the region to be measured on the sample 207, the wavelength and output of the laser light, and the irradiation time of the laser light as inputs to calculate the time it takes to measure the region of the sample 207 with the pulsed electron beam EB, the time it takes for the charge state of the sample 207 to dissipate naturally, the diffusion area of ​​secondary charged particles emitted by irradiation with the pulsed electron beam EB, the distance between multiple parts within the region to be measured on the sample 207, and the settling time of the deflector 205 for high-precision control of the irradiation position of the pulsed electron beam EB. A more specific example will be described later with reference to Figures 4 and 5.

[0033] <Effects of Charging of One Inspection Area on Other Inspection Areas> First, we will explain the effect of charging of an inspection area within the field of view of the charged particle beam apparatus 100 on other inspection areas. Here, the inspection area is an object of observation placed within the field of view of the charged particle beam apparatus 100. Multiple inspection areas can be input by the operator, for example, using an input device 211b. The field of view is the region in which the object of observation of the sample 207 can be observed by deflecting the trajectory of the electron beam EB of the charged particle beam apparatus 100.

[0034] Figure 2 is a schematic diagram showing an example of waveform data obtained by the charged particle beam apparatus 100 of the embodiment. Figure 3 is a schematic diagram showing an example of the situation when the electron beam EB is irradiated to the nearest adjacent inspection area by the charged particle beam apparatus 100 of the embodiment.

[0035] The controller 210 moves the stage 208 on which the sample 207 to be measured is placed, and while controlling the main unit 200 based on the coordinate data of the stage 208 and the area of ​​the sample 207 to be measured (position coordinate data of multiple parts within the field of view), it sequentially irradiates the multiple parts of the sample 207 to be measured with a pulsed electron beam EB.

[0036] The controller 210 detects the secondary charged particles emitted by the irradiation of the electron beam EB using the detector 209 and obtains waveform data, for example, shown in Figure 2, based on the transient response characteristics of the part of the sample 207 to be measured.

[0037] In Figure 2, the horizontal axis represents the time axis, and the vertical axis represents the luminance (detection signal). Upon irradiation with the electron beam EB, secondary charged particles are detected, and at time T1, the luminance increases from luminance V1 to luminance V2, as shown by the amplitude width W. Subsequently, the luminance value converges exponentially, reaching luminance VC (focused value) at time T2. After reaching luminance VC, the luminance rapidly decreases to luminance V1.

[0038] The controller 210 can calculate the amplitude value W1, convergence value VC, and time constant K by applying a fitting function to the waveform data shown in Figure 2. Hereinafter, the amplitude value W1, convergence value VC, and time constant K will be referred to as waveform parameters. By setting thresholds for the waveform parameters, the operator can determine whether a part of the sample 207 to be measured is normal or abnormal, and can also classify or evaluate defects based on electrical characteristics such as electrical resistance and capacitance C.

[0039] Now, consider the case where a pulsed electron beam EB is irradiated onto one of the multiple inspection sites P1 within the field of view of the sample 207, as shown in Figure 3. Secondary charged particles and the like emitted in response to the irradiation of this electron beam EB propagate to the nearest adjacent inspection site P2. As a result, charge accumulates at inspection site P2.

[0040] When the charged particle beam apparatus 100 performs a measurement using a pulsed electron beam EB on an inspection site P2 where charge has accumulated, the amount of emitted secondary charged particles (e.g., secondary electrons) decreases due to the influence of the accumulated charge.

[0041] Therefore, even if the structure and material of each inspection site P1 and P2 present in the sample 207 are identical, if the charged particle beam apparatus 100 performs measurements using a pulsed electron beam EB, different results will be obtained for each measurement of inspection sites P1 and P2. Consequently, the inspection accuracy and measurement accuracy of the charged particle beam apparatus 100 using a pulsed electron beam EB will decrease.

[0042] <Data Input Processing> Before describing the inspection order modification process described in this disclosure, the data input and output processes necessary to perform the modification process will be explained. Figure 4 is a diagram showing an example of the input / output processing of the computer system 212. Figure 5 is a diagram showing an example of the output result of the parameter output.

[0043] When inspecting the sample 207 using the charged particle beam apparatus 100, the operator first inputs the conditions related to the inspection using the input device 211b. The input condition data is, for example, as shown in FIG. 4, charged particle optical condition data 303a, pulsed electron irradiation parameter data 303b, structure data 303c, material data 303d, laser irradiation condition data 303e, inspection FOV size data 303f, and design data 303g. For example, the operator can operate the input device 211b to display a predetermined screen on the display device 211a and input these data from the displayed screen.

[0044] The operator first inputs the charged particle optical condition data 303a. The charged particle optical condition data 303a is, for example, the value of the acceleration voltage of the electron beam EB and the value of the probe current. Predetermined values are used for these. Also, using the input charged particle optical condition 303a, an electron beam scattering simulation (charged particle beam scattering simulation) 301 that simulates the state in which the particles of the electron beam EB irradiated on the sample 207 are scattered is executed. When the electron beam scattering simulation 301 is executed, scattered electron beam diffusion region data 302 of scattered electrons (scattered charged particles) is generated. The scattered electron beam diffusion region data 302 is input to the arithmetic unit 304.

[0045] Furthermore, instead of using the electron beam scattering simulation 301, the arithmetic unit 304 may use, for example, a method of selecting from a list of electron beam scattering models composed of a plurality of previously prepared calculation formulas, a method of performing electromagnetic field simulation on the structure data 303c, or a method combining these methods.

[0046] Subsequently, the operator inputs into the arithmetic unit 304 the pulse electron irradiation parameter data 303b indicating the irradiation position coordinates of the electron beam EB, the structure data 303c indicating the structure of the sample 207, the material data 303d indicating the material of the sample 207, the laser irradiation condition data 303e indicating the irradiation conditions of the laser beam, the inspection FOV size data 303f indicating the size of the field of view to be inspected, and the design data 303g indicating the conditions used when manufacturing the sample 207. In this way, the inspection condition data is inputted.

[0047] When the inspection condition data is inputted as described above, calculations are executed by the arithmetic unit 304 using the condition data shown in FIG. 4. When the calculations are executed by the arithmetic unit 304, parameter data 305 is outputted. The parameter data 305 is registered in the database 212a of the computer system 212. Also, the above-mentioned condition data is registered in the database. As a result, each time the controller 210 inspects the sample 207, it becomes possible to acquire the pre-registered data from the database 212a.

[0048] FIG. 5 is a diagram showing an example of the parameter data 305. The parameter data 305 includes, for example, measurement conversion distance data 305a, deflector static time data 305b, charge removal completion time data 305c, discharge time data 305d, and measurement time data 305e per 1 FOV. The data 305a to 305d included in the parameter data 305 may be obtained, for example, in advance using the measurement target within the sample 207, or may be obtained from a simulation based on the structure data 303c and the material data 303d.

[0049] The measurement conversion distance data 305a is data indicating the distance between an arbitrary inspection site and the next inspection site to be measured. The arithmetic unit 304 can obtain the distances between a plurality of inspection sites within the area to be measured of the sample 207 based on the diffusion region of the secondary charged particles, the inspection FOV size data 303f, and the design data 303g.

[0050] The deflector stabilization time data 305b is data indicating the time it takes for the control of the deflector 205 to stabilize. The calculator 304 can use the distances between multiple inspection sites, i.e., the measurement conversion distance data 305a and the charged particle optical condition data 303a, to determine the stabilization time of the deflector 205, which controls the irradiation position of the pulsed electron beam EB with high precision.

[0051] The static discharge completion time data 305c is data indicating the completion time until the charge on the charged inspection area is removed by the laser light irradiation device 217. The calculator 304 can determine the time required to eliminate the charge formed on the surface of the sample 207 (static discharge) by using the structural data 303c, material data 303d, and laser irradiation condition data 303e.

[0052] The discharge time data 305d is data indicating the time it takes for the accumulated charge to naturally discharge from the inspection area of ​​the sample 207. The calculator 304 can determine the time it takes for the inspection area of ​​the sample 207 to naturally discharge from the structural information data 03c, material data 303d, charged particle optical condition data 303a, and pulsed electron irradiation parameter data 303b.

[0053] The measurement time data 305e per FOV (field of view) is data indicating the time required to measure multiple inspection sites included in one field of view. The arithmetic unit 304 can calculate the measurement time for one of the multiple inspection sites located within the area to be measured of the sample 207 from the design data 303g, pulsed electron irradiation parameter data 303b, and laser irradiation condition data 303e. Therefore, the arithmetic unit 304 can also determine the measurement time for a single field of view.

[0054] Here, the arithmetic unit 304 can pre-determine the position coordinates of multiple inspection sites within the field of view to be measured of the sample 207 using the design data 303g. Alternatively, the arithmetic unit 304 can obtain position coordinates determined by the operator using the display device 211a and the input device 211b. Furthermore, the arithmetic unit 304 determines the static destabilization time of the deflector 205 based on the longest distance between the inspection sites, using the design data 303g or the position coordinates determined by the operator.

[0055] Next, two processes for determining the order in which to examine multiple examination sites within a single field of view (the first examination order and the second examination order calculation process) will be explained with reference to Figures 6 and 7.

[0056] Figure 6 is a flowchart showing an example of the process for determining the first inspection order. The calculation process for the first inspection order is a process for determining the inspection order without using a process to remove static electricity from the inspection area by the laser light irradiation device 217. The first inspection order is calculated so that no two inspection areas are adjacent when multiple inspection areas are arranged within the field of view such that the distance between any two inspection areas is such that they have an electrical influence on each other when the electron beam EB is irradiated.

[0057] The operator uses the display device 211a and input device 211b to register the coordinates of multiple inspection sites within a single field of view, i.e., multiple irradiation positions of the electron beam EB, on the graphical user interface (GUI) displayed on the display device 211a. As a result, as shown in Figure 6, in step S401, the arithmetic unit 304 registers the irradiation position coordinates indicating the irradiation positions of the electron beam EB within a single field of view. The inspection order at this time can be determined by the operator, for example. For example, the initial inspection order may be the order in which the inspection sites were entered.

[0058] In the following step S402, the arithmetic unit 304 calculates the static destabilization time of the deflector 205 based on the distance between irradiation position coordinates (also called the distance between inspection areas) calculated based on the irradiation position coordinates registered in step S401. Next, in step S403, the arithmetic unit 304 compares the parameter data 305, which was explained with reference to Figure 5, with the static destabilization time of the deflector 205 calculated in step S402.

[0059] In step S404, the arithmetic unit 304 compares the settling time of the deflector 205 with the discharge time of the charge at the inspection site calculated based on the condition data, and calculates the inspection order based on the result of the comparison. In this embodiment, the arithmetic unit 304 determines whether the settling time of the deflector 205 is less than the natural discharge time. If the settling time of the deflector 205 is greater than or equal to the natural discharge time (S404: NO), in step S405, the arithmetic unit 304 registers the inspection order of multiple inspection sites so that adjacent inspection sites become the next inspection sites. In this case, for example, as explained with reference to Figure 2, the effect of discharge from the inspection site irradiated with the electron beam EB is completed before the inspection at the next inspection site begins, so there is no need to consider the order in which the electron beam EB is irradiated. For this reason, the arithmetic unit 304 can register the order entered by the operator as the inspection order.

[0060] On the other hand, if the static desting time of the deflector 205 is less than the natural discharge time (S404: YES), in step S406, the arithmetic unit 304 starts the optimal coordinate search process. For example, in the optimal coordinate search process, the inspection order is rearranged, and the distance between the rearranged inspection parts is calculated. Here, the rearrangement is calculated so that the static desting time exceeds the discharge time. For example, in the field of view, the inspection order is calculated so that no two inspection parts are adjacent to each other.

[0061] Next, in step S407, the calculator 304 determines whether the distance between the inspection sites is outside the diffusion region of secondary charged particles. This determination is made because if the distance between the inspection site irradiated by the electron beam EB and the next inspection site is not outside the diffusion region of secondary charged particles calculated by the process shown in Figure 5, the next inspection site will be charged by secondary charged particles and will be unsuitable as the next inspection site.

[0062] If the distance between the inspection sites is not outside the diffusion region of secondary charged particles (S407: NO), the process returns to step ST406, and the arithmetic unit 304 rearranges the next candidate inspection order and calculates the distance between the rearranged inspection sites. The process is looped in this manner until an inspection site is found in which the distance between all inspection sites is outside the diffusion region of secondary charged particles.

[0063] On the other hand, if it is determined that the distance between the inspection sites is outside the diffusion region of secondary charged particles (S407: YES), in step S408, the arithmetic unit 304 registers the inspection order of the rearranged inspection sites in step S406. This process is performed for multiple inspection sites, and the first inspection order is calculated.

[0064] By performing inspections in the order determined as described above, the charged particle beam apparatus 100 can eliminate the effect of the inspection area becoming charged due to irradiation with the electron beam EB, thereby improving inspection accuracy and measurement accuracy. Therefore, the charged particle beam apparatus 100 can avoid the influence of the charge on other inspection areas caused by the charging of one inspection area.

[0065] Figure 7 is a flowchart showing an example of the process for determining the second inspection order. The process for calculating the second inspection order is a process for determining the inspection order using a process that removes static charge from the inspection area using the laser light irradiation device 217. In this embodiment, if the static desistance time of an inspection area is less than the discharge time, the second inspection order is calculated so that a process of removing static charge using the laser light irradiation device 217 is added for that inspection area. Note that the processes in steps S501 to S505 shown in Figure 7 are the same as the processes in steps S401 to S405 shown in Figure 6, so their explanation is omitted, and the process will be explained starting from step S506.

[0066] As shown in Figure 7, if the static desting time of the deflector 205 is less than the natural discharge time (S504: YES), in step S506, the arithmetic unit 304 compares the static desting time of the deflector 205 with the static desisting completion time. Here, the static desisting completion time is the time until the surface of the sample 207 is destaticized by the laser light irradiated by the laser light irradiation device 217.

[0067] If the static desting time of the deflector 205 is not less than the static discharge completion time (S506: NO), in step S505, the calculator 304 registers the inspection site as the next inspection site. When the calculator 304 makes such a registration, for example, it adds data indicating that laser light irradiation is required for the inspection site.

[0068] For inspection sites registered in this manner, even if, for example, an electric charge accumulates during inspection due to irradiation by the electron beam EB of the inspection site being inspected immediately before, the charged particle beam apparatus 100 can irradiate the inspection site with laser light using the laser light irradiation device 217 to remove the charge. For this reason, the arithmetic unit 304 can register an inspection site even if the static desting time of the deflector 205 is not less than the charge removal completion time.

[0069] On the other hand, if the static desting time of the deflector 205 is less than the static discharge completion time (S506: YES), the arithmetic unit 304 executes the processes in steps S507 to S509. The processes in steps S507 to S509 are the same as the processes in steps S406 to S408 shown in Figure 6, so their explanation is omitted. Such processes are performed for multiple inspection sites, and the second inspection sequence is calculated.

[0070] Similar to the process described in Figure 6, by performing inspections in a determined inspection sequence, the charged particle beam apparatus 100 can eliminate the effect of the inspection area becoming charged due to irradiation with the electron beam EB, thereby improving inspection accuracy and measurement accuracy. Therefore, the charged particle beam apparatus 100 can avoid the influence of the charging of one inspection area on other inspection areas in a different manner from the first inspection sequence by using laser light from the laser light irradiation device 217 to decharge the inspection area.

[0071] Here, the inputs for step S401 in Figure 6 and step S501 in Figure 7 are registered, for example, via the graphical user interface shown in Figure 8, which will be described later, but are not limited to this. For example, the design data 303g of sample 207, which was explained with reference to Figure 4, may be used. When the design data 303g is used, the irradiation position coordinates of the electron beam EB are automatically determined. The irradiation position coordinates may be assigned to the inspection order, for example, with the leftmost of the multiple inspection areas in the field of view as the starting point, and the nearest inspection area as the next irradiation position coordinate. When applying the process shown in the flowchart of Figure 6 or Figure 7 at this time, the process may start from steps S403 and S503, respectively.

[0072] Figure 8 shows an example of the coordinate registration GUI 601 displayed on the display device 211a. The coordinate registration GUI 601 has the function of accepting the input of the above-mentioned condition data, and the function of causing the arithmetic unit 304 to execute the processing of the flowcharts shown in Figures 6 and 7.

[0073] As shown in Figure 8, the coordinate registration GUI 601 includes, for example, a coordinate display area 602 for irradiating with a pulsed electron beam EB, a condition display area 603 for displaying input condition data such as the acceleration voltage, probe current, magnification, pulse width, and number of pulses of the electron beam EB, an irradiation condition display area 604 for displaying the irradiation conditions of the laser light, and a field of view display area 605 for displaying the area (field of view: FOV) to be measured of the sample 207. The field of view display area 605 displays multiple inspection areas 605a and the inspection order (for example, see Figure 9, which will be described later).

[0074] Furthermore, the coordinate registration GUI 601 displays a button section 606 that instructs the system to automatically rearrange the inspection order according to the flowcharts shown in Figures 6 and 7. The button section 606 is equipped with a "Throughput" button 606a, a "High-Precision 1" button 606b, and a "High-Precision 2" button 606c.

[0075] If the "Throughput" button 606a is selected, the arithmetic unit 304 determines the irradiation order of the pulsed electron beam EB, i.e., the inspection order, so as to minimize the settling time of the deflector 205. If the "High-Precision 1" button 606b is selected, the arithmetic unit 304 executes the flowchart shown in Figure 6 to determine the inspection order. If the "High-Precision 2" button 606c is selected, the arithmetic unit 304 executes the flowchart shown in Figure 7 to determine the inspection order. The inspection order may also be determined in an order set by the operator.

[0076] Figure 9 shows an example of the display in the field of view display area 605. Multiple inspection areas 605a are displayed in the field of view display area 605. The numbers within the inspection areas 605a indicate the inspection order of the multiple inspection areas. In this embodiment, the multiple inspection areas are divided into multiple rows, and multiple inspection areas are set in each row. The inspection order is from the left end to the right end of the upper row, and progresses from the upper row to the lower row. This inspection order is entered, for example, by the operator. The example of displaying the inspection order shown in Figure 9 is just one example, and the inspection order may be displayed in any way as long as the inspection order is visible.

[0077] This section explains what happens when the "High-Precision 1" button 606b is selected while the inspection order is displayed in this manner.

[0078] Figure 10 shows an example of the distance between inspection areas. In Figure 10, the distance between inspection areas is displayed on the display unit 605P based on a portion of the multiple inspection areas 605a shown in Figure 9. Here, the distance between inspection areas will be explained focusing on inspection area 605a1. Inspection area 605a2 is an inspection area adjacent to inspection area 605a1, and the distance between inspection areas is distance d1. Inspection area 605a3 is an inspection area located further away from inspection area 605a1 than inspection area 605a2, and the distances between inspection areas are distance d2 (>d1) and d3 (>d1). Distance d1 is the distance that does not satisfy the condition "static determination time < natural discharge time" in step S404 shown in Figure 6, and distance d2 is the distance that satisfies the same condition.

[0079] Therefore, in the example shown in Figure 10, if the "High-Precision 1" button 606b is selected, none of the inspection areas 605a2 will be selected as the inspection area to be inspected after inspection area 605a1, and one will be selected from among the inspection areas 605a3. This process is performed, and the arithmetic unit 304 determines the inspection order so that the distance between inspection areas is not d1, but is d2 or greater. In this way, when multiple inspection areas are arranged in the field of view, the inspection order is calculated so that no inspection area 605a1 and the next inspection area are adjacent to each other.

[0080] Next, the "High-Precision 1" button 606b is selected, and the inspection order rearranged by the arithmetic unit 304 will be explained. Figure 11 shows an example of the display of the field of view display area 605. In Figure 11, the inspection order of multiple inspection sites 605a has been rearranged. As shown in Figure 11, adjacent inspection sites are not set as the next inspection sites. For example, the distance between the first inspection site 605a and the second inspection site 605a is d3 (>d1), and the distance between the second inspection site 605a and the third inspection site 605a is d2 (>d1).

[0081] In this way, by pressing the "High-Precision 1" button 606b, the operator can visually confirm that the inspection order of multiple inspection sites within the field of view has been changed. Furthermore, the operator can select the process of changing the inspection order using the multiple buttons provided on the button unit 606, namely the "Throughput" button 606a, the "High-Precision 1" button 606b, and the "High-Precision 2" button 606c. Therefore, the operator can change the inspection order considering the type and material of the sample 207, as well as the inspection time.

[0082] Figure 12 shows an example of log 701. Log 701 is stored, for example, when the inspection order is changed. This log 701 is stored, for example, in the database 212a of the computer system 212. Figure 12 shows an example of the log when the "High-Precision 2" button 606c is selected and the process shown in the flowchart in Figure 7 is executed.

[0083] As shown in Figure 12, the log 701 has a region 701a for storing the irradiation conditions of the electron beam EB, a region 701b for storing the irradiation conditions of the laser light, a region 701c for storing the irradiation position coordinates (Original coordinate for inspection area) based on the design data 303g or coordinates entered by the operator from the GUI 605 shown in Figure 9, a region 701d for storing the irradiation position coordinates (Calculated coordinate for inspection area (Throughput)) when the "Throughput" button 606a is pressed, and a region 701e for storing the irradiation position coordinates (Calculated coordinate for inspection area (High-precision 2)) when the "High-Precision 2" button 606c is pressed. This allows the operator to refer to past logs 701 when having the arithmetic unit 304 execute a process to change the inspection order at a later date.

[0084] Furthermore, log 701 can also store data entered by the operator from the design data 303g or the GUI 605 shown in Figure 9. In addition, when the "High-Precision 1" button 606b is pressed, a new area is created between area 701d and area 701e, and the irradiation position coordinates (Calculated coordinate for inspection area (High-precision 1)) when the "High-Precision 1" button 606b is pressed are stored in this newly created area. In this way, when multiple inspection sequence changes are made, the charged particle beam device 100 can store the coordinate position data of the changed inspection sequence according to the type of button provided on the button section 606. This makes it even more convenient for the operator to use log 701 when referring to past logs.

[0085] Although embodiments of this disclosure have been described in detail above, the present invention is not limited to the embodiments described above and can be modified in various ways without departing from the gist of the invention. Each embodiment can be modified by adding, deleting, or replacing components, except for essential components. Unless otherwise specified, each component may be singular or plural. Combinations of each embodiment and its variations are also possible. Each of the above-described configurations, functions, and processing units may be implemented in part or in whole by hardware, such as by designing an integrated circuit, or by software, such as by a processor interpreting and executing a program. Data such as programs, tables, and files that implement each function can be stored in a recording device such as memory, a hard disk, or an SSD, or on a recording medium such as an IC card, an SD card, or a DVD.

[0086] 100...Charged particle beam apparatus, 200...Main unit, 201...Charged particle gun, 202...Condenser lens, 203...Pulse modulator, 204...Aperture, 205...Decliner, 206...Objective lens, 207...Sample, 208...Stage, 209...Detector, 210...Controller 210, 211a...Display device, 211b...Input device, 212...Computer system, 212a...Database, 217...Laser light irradiation device, 304...Calculator, 601...Coordinate registration GUI, 605...Field of view display area, 605a...Inspection area, 606...Button section, 701...Log, EB...Electron beam

Claims

1. A charged particle beam apparatus for irradiating a sample with a charged particle beam and observing the sample by generating an image based on secondary charged particles generated by the irradiated charged particle beam, comprising: a charged particle beam irradiation optical system for irradiating the sample with the charged particle beam; and a computer system for controlling the charged particle beam irradiation optical system, wherein the charged particle beam irradiation optical system can irradiate the sample with the charged particle beam for each of a plurality of inspection areas within the field of view by deflecting the trajectory of the charged particle beam; and the computer system calculates an inspection order for irradiating the inspection areas with the charged particle beam so as not to impart any electrical effect of the charged particle beam irradiated to any of the plurality of inspection areas to be inspected next, and sequentially irradiates the plurality of inspection areas with the charged particle beam in the calculated inspection order.

2. A charged particle beam apparatus according to claim 1, wherein the computer system acquires condition data including at least one of the structural data of the sample and the material data of the sample, and calculates the inspection sequence based on coordinate position data indicating the coordinate positions of the plurality of inspection sites and the condition data.

3. A charged particle beam apparatus according to claim 2, wherein the charged particle beam irradiation optical system includes a deflector that controls the position at which the charged particle beam is irradiated onto the sample, and the computer system compares the settling time until the deflector settles with the discharge time of the charge of the inspection site calculated based on the condition data, and if the settling time is less than the discharge time, calculates the inspection sequence such that the settling time exceeds the discharge time.

4. A charged particle beam apparatus according to claim 3, wherein the computer system, when calculating the inspection sequence, calculates the inspection sequence such that, when the plurality of inspection sites are arranged within the field of view, the distance between any inspection site and the next inspection site is such that they have an electrical influence on each other when the charged particle beam is irradiated, the distance between any inspection site and the next inspection site is such that the inspection sequence is such that the distance between any inspection site and the next inspection site is such that the distance between the inspection sites and the next inspection site is such that the distance between the inspection sites and the next inspection site is such that they have an electrical influence on each other.

5. A charged particle beam apparatus according to claim 4, further comprising an interface for receiving input of the condition data.

6. A charged particle beam apparatus according to claim 5, further comprising a laser light irradiation device for removing the charge accumulated on the inspection area of ​​the sample.

7. A charged particle beam apparatus according to claim 6, wherein the computer system is capable of calculating a first inspection sequence calculated such that no arbitrary inspection site and the next inspection site are adjacent in the field of view, and a second inspection sequence in which, in the case of an inspection site where the static desting time is less than the discharge time, a process of removing the charge by the laser light irradiation device is added to the inspection site, and the interface receives instructions to cause the computer system to calculate the first inspection sequence or the second inspection sequence.

8. A charged particle beam apparatus according to claim 7, wherein the computer system further comprises a database for storing at least one of the first inspection sequence and the second inspection sequence in association with the condition data.

9. A charged particle beam apparatus according to claim 1, wherein the computer system comprises a charged particle simulation unit that simulates the state in which charged particles irradiated onto a sample diffuse, and calculates the inspection sequence using the results of the simulation by the charged particle simulation unit.

10. A charged particle beam apparatus according to claim 1, wherein the computer system determines whether the electrical effect will affect the next inspection site based on the distance between any inspection site and the next inspection site to be inspected, the time required to deflect the trajectory of the charged particle beam after irradiating the arbitrary inspection site with the charged particle beam in order to irradiate the next inspection site with the charged particle beam, and the time required for the inspection site to naturally discharge after being irradiated with the charged particle beam, and calculates the inspection order using the determination result.

11. A charged particle beam apparatus according to claim 1, comprising: a stage on which a sample is placed; and a stage moving mechanism for moving the stage, wherein the computer system controls the stage moving mechanism.

12. A method for calculating the inspection sequence of a charged particle beam apparatus, which irradiates a sample with a charged particle beam and observes the sample by generating an image based on secondary charged particles generated by the irradiated charged particle beam, wherein the charged particle beam apparatus comprises: a charged particle beam irradiation optical system for irradiating the sample with the charged particle beam; and a computer system for controlling the charged particle beam irradiation optical system, wherein the charged particle beam irradiation optical system can irradiate the sample with the charged particle beam for each of a plurality of inspection sites within a field of view by deflecting the trajectory of the charged particle beam, and the inspection sequence calculation method comprises: calculating an inspection sequence in which the charged particle beam is irradiated to an inspection site such that the electrical effect of the charged particle beam irradiated to any of the plurality of inspection sites is not applied to the inspection site to be inspected next; and sequentially irradiating the plurality of inspection sites with the charged particle beam in the calculated inspection sequence.

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